Based on the assessment of FreedomHawk :
I am not going to distinguish "populist" states from others. Populism as a rule is cyclical, and very weak now (unless one wishes to consider the Tea Party Movement "populist". Most Southern states have latent populism, which explains why Jimmy Carter was able to defeat Gerald Ford with a Democratic Party much more liberal in voting than most of the North and West. To explain how the cycle works, Al Gore and Bill Clinton are from two of the states that you consider 'hardcore conservative. West Virginia used to be very left-wing on economics. The pendulum could swing in those states in the next twenty years.
"Centrist" is white.
Libertarian is more persistent, and it is anti-populist. The paler green is for the more liberal of libertarian states, medium green is for the centrist libertarian states, and dark green is for the conservative libertarian states.
Because blue is associated (Atlas colors) with Republicans and red is associated (Atlas colors) with Democrats, those colors are in use and I associate intensity of liberalism or conservatism with the intensity of hue.
I have made guesses on the three districts of Nebraska. DC is in a class of its own, and NE-03 is the most-decidely right-wing unit of electoral votes in America.
We shall soon change this map based on 2014 elections.